1. Field of the Invention
The present invention relates generally to the wireless communication industry, and, more specifically, relates to a wireless cell phone signal booster (repeater).
2. Description of Related Art
Cellular telephones have limited ranges for receiving signals from cellular towers and for transmitting signals to cellular towers. When a cellular telephone is in a fringe area (e.g., an area located a substantial distance away from the nearest tower or an area located near obstacles that partially block cellular signals), the user of the telephone may not have any reception or may have very poor reception. Generally, the reception could be improved if the cellular telephone had more power; however, the power is limited by regulations and by the size of the telephone.
In some applications, radio frequency (RF) signal boosters (repeaters) can be used. RF signal boosters receive, amplify and simultaneously re-transmit radiated RF signals with no frequency conversion. Historically, the signal amplification (gain) performance of such devices has been determined by the amount of isolation that can be achieved between transmit and receive antennas. If the gain exceeds the amount of isolation between transmit and receive antennas, the RF amplifier will become unstable (e.g., oscillate), thereby causing unwanted spurious signals to be generated. Since cellular telephones are often used in offices, houses or vehicles where only a limited  amount of space is available for placement of the transmit and receive antennas, it previously was considered impractical or infeasible to provide a signal booster for a cellular telephone system.